Molecular characterization and comparative analysis of four new genes from Sec2 locus encoding 75K γ-secalins of rye species

Using a PCR-based strategy, four new 75K γ-secalin genes were isolated from Secale cereale, Secale vavilovii, Secale sylvestre, and Secale strictum in genus Secale (rye). Based on amino acid sequences, the primary structure of the 75K γ-secalin subunits was demonstrated, which was composed of four main structural regions: (a) a conservative 19 amino acids signal peptide, (b) a steady short N-terminal region of 12 amino acids containing a cysteine residue, (c) a repetitive domain, which began with the conservative tetrapeptides PQ₃ and was rich in glutamine and proline. PFPQ₁₋₂(PQQ)₁₋₂ was the core repeat motif in the repetitive region. Besides amino acid substitutions, this region showed variations in length due to the insertion and deletion events. In the repetitive region of EF432549 (Secale strictum), there were two octapeptides (PFPQQPQQ and PVPQQSQQ) insertions. On the contrary, deletion events of two residues (QT) took place in EF432546 (Secale sylvestre). Accounting for the amino acid replacement, an extra cysteine residue appeared in the repetitive region of EF432546, which did not exist in other genes, and (d) a conserved 143 amino acids C-terminal domain including eight cysteine residues. The implications of the results for quality improvement are discussed.     

Physicochemical measurements in ‘Mondial Gala’ apples stored at different atmospheres: Influence on consumer acceptability

Standard quality parameters, consumer acceptability, emission of volatile compounds and ethylene production of ‘Mondial Gala^®’ apples (Malus × domestica Borkh.) were determined in relation to storage atmosphere, storage period and shelf-life period. Fruit were harvested at the commercial date and stored in AIR (21 kPa O₂:0.03 kPa CO₂) or under three different controlled atmospheres (CAs): LO (2 kPa O₂:2 kPa CO₂), ULO1 (1 kPa O₂:1 kPa CO₂), or ULO2 (1 kPa O₂:2 kPa CO₂). Fruit samples were analysed after 12 and 26 weeks of storage plus 1 or 7 d at 20 °C.Apples stored in CA maintained better standard quality parameters than AIR-stored fruit. The volatile compounds that contributed most to the characteristic aroma of ‘Mondial Gala^®’ apples after storage were butyl, hexyl and 2-methylbutyl acetate, hexyl propanoate, ethyl butanoate, ethyl hexanoate, ethyl, butyl and hexyl 2-methylbutanoate. Data obtained from fruit analysis were subjected to principal component analysis (PCA). The apples most accepted by consumers showed the highest emission of ethyl 2-methylbutanoate, ethyl hexanoate, tert-butyl propanoate and ethyl acetate, in addition to the highest titratable acidity and firmness values.     

The effect of delays in establishment of a static or dynamic controlled atmosphere on the quality of ‘Hass’ avocado fruit

The effect of delays of 1, 5, 10 or 15 d after harvest in establishing a static controlled atmosphere (SCA) or dynamic controlled atmosphere (DCA) on the quality of ‘Hass’ avocados (Persea americana Mill.) was investigated. Fruit were stored at 5 °C in SCA (5% O₂/5% CO₂) or DCA (<3% O₂/0.5% CO₂) for 6 weeks and compared with fruit stored in air. In addition, to determine whether increasing the CO₂ in the DCA would affect the fruit quality, DCA-stored fruit were compared with fruit held in a DCA with 5% CO₂ (DCA + CO₂) established 1 d after harvest. The quality of fruit was assessed at the end of storage and after ripening at 20 °C. DCA-stored fruit ripened in 4.6 d compared with 7.2 d for SCA-stored fruit, or 4.8 d for air-stored fruit. In addition, the incidences of stem end rot (SER), body rot (BR) and vascular browning (VB) were lower in DCA-stored fruit (35%, 29% and 29%, respectively) than in SCA-stored fruit (57%, 52% and 49%, respectively), or air-stored fruit (76%, 88% and 95%, respectively). Delaying the establishment of both SCA and DCA for 15 d resulted in significantly more advanced skin colour at the end of storage (average rating score 11.9) compared with other delay periods (4.6–5.1). There was no significant effect of delay on the time to ripen, skin colour when ripe or any ripe fruit disorder incidence. The incidence of diffuse flesh discolouration (DFD) was not only <1% when averaged over all delays but only occurred at >0.5% incidence in the 15 d delay treatment in DCA (4.8%) and not in SCA. The incidence of diffuse flesh discolouration was 62% in air-stored fruit. Inclusion of 5% CO₂ in DCA retarded fruit ripening from 4.7 to 6.9 d and increased the incidence of rots at the end of storage from 5% to 14%, and increased the incidence in ripe fruit of SER from 30% to 56% and of BR from 27% to 55%. It is concluded that fruit quality was better after CA storage than after air storage, and that DCA storage was better than SCA. The effect of DCA is to independently reduce the time to ripen after storage and the incidence of rots when ripe. Delaying the application of SCA or DCA did not affect the expression of rots, but may increase the incidence of DFD. Inclusion of CO₂ at 5% in CA retarded fruit ripening but stimulated rot expression and should not be used for CA storage of New Zealand grown ‘Hass’ avocados.     

凹叶厚朴种子保存方法及幼苗生长规律

对凹叶厚朴的种子保存方式及相应的播种苗的发芽情况、幼苗生长规律进行统计分析。结果表明:冷藏处理的凹叶厚朴种子发芽慢、发芽持续时间长;播种苗株高生长呈"S"型的慢—快—慢的规律,地径与叶幅生长表现出快—慢—快—慢的规律;株高、地径、叶幅三者之间的生长呈极显著正相关;种子经沙藏的凹叶厚朴发芽时间、出苗速度及发芽率均优于冷藏处理,而且,沙藏处理的苗高、地径、叶幅的累积生长量相应地大于冷藏处理。     

紫薇花粉贮藏及花粉活力的分析

分析了3个紫薇品种花粉活力及不同贮藏温度对花粉活力的影响,结果表明:3个紫薇品种鲜花粉活力存在极显著差别.低温有效地延长了花粉活力的保持时间,在4℃条件下,花粉活力保持164.278 h;在-20℃条件下,花粉活力保持141.278 h;在室温条件下,紫薇花粉活力仅保持18.444 h.     

鸡大肠杆菌病多价蜂胶灭活疫苗研究(Ⅱ报)——疫苗免疫持续期、安全性、保存期试验

以鸡大肠杆菌常见致病性血清型O_1、O_2、O_(78)3个血清型菌株制备5批鸡大肠杆菌病多价蜂胶灭活疫苗,并对其进行免疫持续期、安全性及保存期试验。免疫试验效果表明,5批疫苗近期保护率87.5％～100％,6个月保护率75％～87.5％;成年产蛋鸡在产蛋前2周于始免疫,免疫后3个月和6个月抽样攻毒,3个月保护率100％,6个月保护率87.5％以上。安全性试验证明,14日龄肉鸡0.5ml,40日龄蛋鸡注射1ml/只无临床反应,2ml/只,3ml/只剂量组注射后2～4h,产生临床上一过性反应,不引起鸡死亡。该疫苗在10～20℃条件下保存6个月,4～8℃保存18个月,免疫保护效果80％以上,疫苗久置有沉淀,用时需要充分摇匀。     

高温贮运条件对矮牵牛种苗品质的影响

研究在夏季无调温车的高温环境下,基质含水量对矮牵牛种苗贮运品质的影响。结果表明:在温度分别为25℃、35℃和基质含水量分别为80%、50%的不同处理下,矮牵牛种苗出现株高增加、干重下降、叶绿素含量下降等质量劣变问题;较低的基质含水量处理,可以减缓种苗质量劣变的程度。矮牵牛贮藏6 d后,定植成活率显著下降。随着贮藏时间的增加,现蕾时间推迟,平均花数减少,花期缩短,与不贮藏的种苗相比,贮藏4 d后出现显著差异。     

不同处理对龙都早熟柚脱苦效果研究

[目的]寻求简便实用的鲜果脱苦方法。[方法]在采用CT保鲜剂(对照)的基础上,再分别用1%乙醇、5%乙醇、1%醋酸、1%醋酸在(40±1)℃下12 h(、40±1)℃下12 h处理龙都早熟柚,观察不同处理方法的脱苦效果、贮藏效果。[结果]各处理的柚皮苷含量都随贮藏时间的延长而下降,贮藏90 d后,1%醋酸配合高温的处理的柚皮苷含量最低,说明其具有较好的脱苦效果。1%醋酸配合高温的处理及高温处理的龙都早熟柚的Vc、总固形物、总酸含量下降的较多,且加速了龙都早熟柚的衰老。1%醋酸配合高温处理的好果率比对照低10%,保鲜效果较差。[结论]1%醋酸在(40±1)℃下处理12 h对龙都早熟柚有较好的脱苦效果。     

不同包装材料对生菜采后生理及保鲜效果的影响

为探索低温条件下适宜的包装材料,以5种不同包装材料PA/PE、OPP/CPP、HDPE、PE、PD961包装的生菜为研究对象,研究不同包装材料对生菜采后生理及保鲜效果的影响。结果表明:经过包装处理的生菜贮藏效果优于无包装组,其中HDPE包装材料较好地保持了叶用生菜的叶绿素含量和感官品质,延缓了呼吸高峰的出现、抑制PPO酶活性,贮藏效果最好。不同包装材料对生菜采后生理及保鲜效果存在明显差异,其效果依次为HDPEOPP/CPPPEPA/PEPD961。     

贮藏温度对鸡腿蘑采后生理和品质的影响

以新鲜鸡腿蘑为试验材料,研究了不同贮藏温度及贮藏温度波动对其采后若干生理特性和品质的影响。结果表明,适宜且稳定的低温可降低鸡腿蘑的呼吸强度,抑制采后开伞、失重、褐变、菇柄伸长及抽空等后熟衰老现象;而贮藏温度的波动则会增强鸡腿蘑的呼吸作用,提高呼吸强度,使其鲜度指数明显降低,严重影响了鸡腿蘑的采后品质和商品价值。